1. Field of the Invention
The present invention relates to a baseplate of a disk drive suspension, and more particularly, to a baseplate free from sticking during manufacture.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing device such as a personal computer. The HDD comprises a magnetic disk rotatable about a spindle, a carriage arm (actuator arm) turnable about a pivot, etc. A disk drive suspension (hereinafter simply referred to as a “suspension”) is disposed on the distal end portion of the actuator arm.
The suspension comprises a baseplate, load beam, flexure, etc. The baseplate is fixed to the actuator arm. The load beam is mounted on the baseplate. The flexure is located along the load beam. A slider is mounted on a tongue portion formed on the flexure. A transducer is disposed on the slider. The transducer is an element for reading or writing.
As described in Jpn. Pat. Appln. KOKAI Publications Nos. 2007-287296, 2008-004142, and 7-192420, the baseplate of the suspension is fixed to a suspension bearing surface of the actuator arm. For example, a boss portion formed on the baseplate is inserted into a hole in the actuator arm. The baseplate is fixed to the actuator arm in such a manner that the boss portion is pressed by a jig from the inside and expanded by plastic deformation.
As one such method in which the baseplate is fixed to the actuator arm by expanding the boss portion as described above, there is a diameter expanding process such as ball caulking disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-192420. In this diameter expanding process, the boss portion of the baseplate is fitted into the hole in the actuator arm. A steel ball for use as a caulking jig is press-fitted into the hole in the boss portion through one opening and discharged through the other opening. Thereupon, the diameter of the boss portion is expanded. The expanded boss portion is tightly fitted to the inner surface of the hole in the actuator arm. Consequently, the baseplate is fixed to the actuator arm.
The baseplate is fabricated by press forming. Since the baseplate is work-hardened, the boss portion is unduly hard. Accordingly, the baseplate is adjusted to a hardness suitable for the diameter expanding process by a heat treatment.
The heat treatment is simultaneously performed for a plurality of baseplates. In this heat treatment, a large number of baseplates are collectively charged at random into a heating furnace. In some cases, therefore, the baseplates may be heated with their flat surfaces accidentally overlapping one another. If the flat surfaces are in contact with one another as the baseplates are heat-treated, surface substances of the baseplates may sometimes be stuck to one another by, for example, diffusion bonding.
In some cases, moreover, the baseplates may be surface-treated in order to remove solid particulate dust from the surfaces of the baseplates or make the surfaces suitable for the ball caulking. If the flat surfaces of the surface-treated baseplates contact one another, the baseplates may be stuck to one another by a surface tension or the like.
If the baseplates stuck in this manner are forced to be separated, they are inevitably deformed and become unusable. Thus, if the baseplates stick to one another, the yield rate of production is reduced.